Abstract

The connection between East Australian Current (EAC) transport variability and Australia’s east coastsea level has received little treatment in the literature. This is due in part to the complex interactingphysical processes operating in the coastal zone combined with the sparsity of observations available toimprove our understanding of these possible connections. This study demonstrates a statisticallysignificant (at the 490% level) relationship between interannual to decadal time scale variations inobserved estimates of the EAC transport changes and east coast sea level measured at the high-quality,long record Fort Denison tide-gauge in Sydney Harbour, Australia (3315101800S, 15111303200E). Wefurther demonstrate, using a linear reduced-gravity ocean model, that ENSO to decadal time-scalevariations and the ocean-adjusted multi-decadal trend (approx. 1 cm/decade) in observed sea level atFort Denison are strongly connected to modulations of EAC transports by incoming westwardpropagating oceanic Rossby waves. We show that EAC transport and Fort Denison sea level vary in amanner expected from both Tasman Sea generated Rossby waves, which account for the interannualand multi-annual variability, and remotely forced (from east of New Zealand) Rossby wave connectionsthrough the mid-latitudes, accounting for the ocean-adjusted multi-decadal trend observed at the NewSouth Wales coast – with the regional-Tasman Sea forcing explaining the greatest overall proportion ofEAC transport and sea-level variances.